I was going to make a dumb comment about the homoerotic tension of sparring, but seriously this scene tells us a lot about the characters. First, Korra is able to calm down and apologize instead of letting herself lost in her anger. That’s what I call character development. I think she could had gotten there sooner but then season 2 happened and she was sent back to square 1. At least in this season they are allowing her to grow, she stills has flaws but she’s also more keen on working on them.
Second of all, Asami always speaks up when something is bothering her and she’s sincere and open about what she feels and what she wants. She doesn’t let others step over her. We’ve seen her confronting her father and Mako before and it’s good to see her being that way with Korra. She tells her that she’s going too far and Korra is able to listen. I think this could be something that works well in their relationship. Korra has learned to be more mindful of others feelings and Asami isn’t afraid to speak her mind to the Avatar.